Segmentation fault with input containing 24 variables and 9 equations #238
Description
The input:
$ cat input
a_1,a_2,a_3,a_4,a_5,a_6,a_7,a_8,a_9,a_10,a_11,a_12,b_1,b_2,b_3,b_4,b_5,b_6,b_7,b_8,b_9,b_10,b_11,b_12
0
-a_2-2*b_3,
-2*a_3*b_2+2*a_2*b_3-a_6-3*b_7,
-3*a_7*b_2+2*a_6*b_3-2*a_3*b_6-3*a_2*b_7-a_11-4*b_12,
-4*a_12*b_2+2*a_11*b_3-3*a_7*b_6+3*a_6*b_7-2*a_3*b_11+4*a_2*b_12,
-4*a_12*b_6+3*a_11*b_7-3*a_7*b_11+4*a_6*b_12,
-4*a_12*b_11+4*a_11*b_12,
-2*a_1-b_2,
-4*a_3*b_1+4*a_1*b_3-2*a_5-2*b_6,
-6*a_7*b_1-a_6*b_2+4*a_5*b_3-4*a_3*b_5+a_2*b_6+6*a_1*b_7-2*a_10-3*b_11
It raises a Segmentation fault:
$ msolve -f input -g 2 -v 2
--------------- INPUT DATA ---------------
#variables 24
#equations 9
#invalid equations 0
field characteristic 0
homogeneous input? 0
signature-based computation 0
monomial order DRL
basis hash table resetting OFF
linear algebra option 2
initial hash table size 131072 (2^17)
max pair selection ALL
reduce gb 1
#threads 1
info level 2
generate pbm files 0
------------------------------------------
Legend for f4 information
--------------------------------------------------------
deg current degree of pairs selected in this round
sel number of pairs selected in this round
pairs total number of pairs in pair list
mat matrix dimensions (# rows x # columns)
density density of the matrix
new data # new elements for basis in this round
# zero reductions during linear algebra
time(rd) time of the current f4 round in seconds given
for real and cpu time
--------------------------------------------------------
deg sel pairs mat density new data time(rd) in sec (real|cpu)
------------------------------------------------------------------------------------------------------
3 9 9 46 x 120 2.97% 9 new 0 zero 0.00 | 0.00
4 28 30 296 x 624 0.76% 8 new 20 zero 0.00 | 0.00
5 39 40 907 x 2285 0.29% 11 new 28 zero 0.00 | 0.00
6 62 66 3840 x 8331 0.08% 8 new 54 zero 0.01 | 0.01
7 56 59 9898 x 19603 0.04% 9 new 47 zero 0.01 | 0.01
8 68 68 30408 x 54067 0.02% 14 new 54 zero 0.05 | 0.05
9 100 103 102487 x 158680 0.01% 10 new 90 zero 0.19 | 0.19
10 80 80 164467 x 246105 0.00% 12 new 68 zero 0.34 | 0.34
11 89 91 393313 x 549256 0.00% 8 new 81 zero 0.92 | 0.91
12 58 60 459161 x 629834 0.00% 6 new 52 zero 1.03 | 1.03
13 44 51 747094 x 955833 0.00% 2 new 42 zero 1.78 | 1.78
14 16 22 231366 x 314556 0.00% 3 new 13 zero 0.48 | 0.48
15 22 31 1088698 x 1347614 0.00% 2 new 20 zero 2.82 | 2.82
16 17 24 1316137 x 1611550 0.00% 3 new 14 zero 3.41 | 3.41
17 24 28 3101371 x 3743654 0.00% 3 new 21 zero 9.45 | 9.45
18 27 28 4112873 x 4852959 0.00% 3 new 24 zero 13.49 | 13.49
19 22 22 3719714 x 4381914 0.00% 1 new 21 zero 11.49 | 11.49
20 7 7 2153194 x 2535385 0.00% 0 new 7 zero 6.20 | 6.20
------------------------------------------------------------------------------------------------------
reduce final basis 127 x 383158 0.82% 121 new 0 zero 0.26 | 0.26
------------------------------------------------------------------------------------------------------
---------------- TIMINGS ---------------
overall(elapsed) 51.92 sec
overall(cpu) 51.91 sec
select 0.54 sec 1.0%
symbolic prep. 36.30 sec 69.9%
update 0.00 sec 0.0%
convert 8.84 sec 17.0%
linear algebra 3.87 sec 7.5%
reduce gb 0.00 sec 0.0%
-----------------------------------------
---------- COMPUTATIONAL DATA -----------
size of basis 121
#terms in basis 399751
#pairs reduced 768
#GM criterion 6492
#redundant elements 0
#rows reduced 1657
#zero reductions 656
max. matrix data 4112873 x 4852959 (0.000%)
max. symbolic hash table size 2^23
max. basis hash table size 2^23
-----------------------------------------
Learning phase 0.00 Gops/sec
Erreur de segmentation (core dumped)
This is with the msolve currently in sagemath, that is, version 0.6.5. I was able to reproduce the same issue with msolve 0.9.1.